Installation guide

Dynamic Load Balancing with DM-Multipath
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Further Reading
The Storage Administration Guide
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features a chapter that covers I/O Limits in further detail.
4.2. Dynamic Load Balancing with DM-Multipath
Device Mapper Multipathing (DM-Multipath) creates a single conceptual device from the multiple
cables, switches and controllers that connect servers to storage arrays. This enables centralized
management of connection devices (also known as paths) and makes it possible to balance loads
over all available paths.
DM-Multipath in Red Hat Enterprise Linux 6 introduces two new options when dynamically balancing
load over paths. Paths can now be dynamically selected depending on either the queue size of each
path or previous I/O time data.
Further Reading
The DM Multipath
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book provides information on using the Device-Mapper Multipath feature of
Red Hat Enterprise Linux 6.
4.3. Logical Volume Manager (LVM)
Volume management creates a layer of abstraction over physical storage by creating logical storage
volumes. This provides greater flexibility over just using physical storage directly. Red Hat Enterprise
Linux 6 manages logical volumes using the Logical Volume Manager (LVM).
Important
system-config-lvm is a graphical user interface provided in Red Hat Enterprise Linux to
manage logical volumes. The functionality provided by system-config-lvm is in the process
of transitioning to a more maintainable tool named gnome-disk-utility (also referred to as
palimpsest). As a result, Red Hat will be very selective in updating system-config-lvm. As
gnome-disk-utility reaches feature parity with system-config-lvm, Red Hat reserves
the right to remove system-config-lvm during the life of Red Hat Enterprise Linux 6.
Further Reading
The Logical Volume Manager Administration
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document describes the LVM logical volume
manager, including information on running LVM in a clustered environment.
4.3.1. LVM Mirror Improvements
LVM supports mirrored volumes. By creating mirrored logical volumes, LVM ensures that data written
to an underlying physical volume is mirrored onto a separate physical volume.
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http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Storage_Administration_Guide/newstorage-
iolimits.html#iolimits
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http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/DM_Multipath/
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http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Logical_Volume_Manager_Administration/